code: def parse_agent(agent):
      return {
          "DQN": agents.DQN,
          "DoubleDQN": agents.DoubleDQN,
          "PAL": agents.PAL,
      }[agent]
  
file_path: pfrl/examples/atari/train_dqn_ale.py
imports: import argparse
  import numpy
  import torch
  import torch.nn
  import pfrl
  from pfrl import agents, experiments, explorers
  from pfrl import nn
  from pfrl import replay_buffers, utils
  from pfrl.initializers import init_chainer_default
  from pfrl.q_functions import DiscreteActionValueHead, DuelingDQN
  from pfrl.wrappers import atari_wrappers
label_desc: Use image node_id 2 for calling a global function with example usage: parse_agent(agent) and returns: dict